Photo-curable composition and patterning method using the same

ABSTRACT

The present invention provides a photo-curable composition that requires a small demolding force. The present invention also provides a UV imprint method that requires a small demolding force. 
     The photo-curable composition contains a polymerizable monomer (A), a polymerization initiator (B), and a fluorine-containing surfactant (C). A photo-cured product of the photo-curable composition has a water contact angle of 74 degrees or less.

TECHNICAL FIELD

The present invention relates to a photo-curable composition and apatterning method using the photo-curable composition.

BACKGROUND ART

A UV nanoimprint method is a patterning method of pressing a mold havinga fine textured pattern on its surface against a substrate coated with aresist (photo-curable composition) to transfer the textured pattern tothe resist film on the substrate.

It is important in the UV nanoimprint method to decrease the force withwhich the mold is released from cured resist, that is, demolding force.This is because a large demolding force may cause defects in the patternor may cause the substrate to rise from the stage, resulting in lowalignment precision.

A known photo-curable composition for use in photo-nanoimprint containsat least one polymerizable monomer, a polymerization initiator, and afluorinated surfactant.

(PTL 1)

PTL 1 also discloses the use of a fluorinated surfactant in which aperfluoroalkyl chain is bonded to a hydrocarbon chain or a fluorinatedsurfactant in which a perfluoroalkyl chain is bonded to an ethoxy chain,a methoxy chain, or siloxane.

PTL 2 discloses that the resulting photo-cured film is water-repellentand preferably has a water contact angle in the range of 75 to 98degrees.

CITATION LIST Patent Literature

PTL 1 Japanese Patent Laid-Open No. 2007-084625

PTL 2 International Publication WO 2006/114958

SUMMARY OF INVENTION Technical Problem

As described above, it is known that a fluorinated material may be addedto a composition to impart water repellency to a surface of aphoto-cured film and decrease demolding force. However, the addition ofa known fluorinated material alone does not necessarily provide aninterface between a mold surface and a photo-cured film surface thatcontributes to a decreased demolding force, and still results in a largedemolding force.

In view of such problems associated with the related art, the presentinvention provides a photo-curable composition that requires a smalldemolding force in a patterning method. The present invention alsoprovides a patterning method that requires a small demolding force.

Solution to Problem

In order to solve the problems described above, a photo-curablecomposition according to one aspect of the present invention contains apolymerizable monomer (A), a polymerization initiator (B), and afluorine-containing surfactant (C), wherein a photo-cured product of thecomposition has a water contact angle of 74 degrees or less.

A patterning method according to one aspect of the present inventionincludes placing the photo-curable composition on a substrate to beprocessed, bringing the photo-curable composition into contact with amold, irradiating the photo-curable composition with light, andreleasing the photo-curable composition from the mold after theirradiation.

Advantageous Effects of Invention

The present invention provides a photo-curable composition that requiresa small demolding force. The present invention also provides apatterning method that requires a small demolding force.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1A to 1F are cross-sectional views illustrating a patterningmethod.

DESCRIPTION OF EMBODIMENTS

The present invention will be further described in the followingembodiments. The present invention is not limited to these embodiments.It will be recognized by those skilled in the art that variations andmodifications may be made to these embodiments without departing fromthe gist of the present invention. These variations and modificationsare also intended to be within the scope of the present invention.

The term “patterning method”, as used herein, includes a UV imprintmethod. The UV imprint method is preferably defined as a method forforming a pattern having a size in the range of 1 nm to 10 mm, morepreferably approximately 10 nm to 100 μm. A technique of forming ananoscale (1 to 100 nm) pattern (textured structure) is generallyreferred to as photo-nanoimprint. The present invention includesphoto-nanoimprint.

A photo-curable composition according to an embodiment of the presentinvention contains a polymerizable monomer (A), a polymerizationinitiator (B), and a fluorine-containing surfactant (C). Thephoto-curable composition may contain another additive component.

The fluorine-containing surfactant (C) may have a polar functional groupat one end.

The amount of fluorine-containing surfactant (C) is controlled such thata photo-cured product of a photo-curable composition according to anembodiment of the present invention has a water contact angle of 74degrees or less.

As disclosed in PTL 2, it has hitherto been preferable that aphoto-cured film is water-repellent and has a high water contact anglein the range of 75 to 98 degrees.

As a result of extensive studies, the present inventors found that aphoto-curable composition requires a small demolding force when itsphoto-cured product has a water contact angle of 74 degrees or less.

Although there is no clear reason that a composition according to anembodiment of the present invention requires a small demolding forcewhen the contact angle is 74 degrees or less, it is surmised that thefluorine-containing surfactant (C) segregates on a surface of thephoto-cured product, and a terminal functional group of the surfactantimparts hydrophilicity to the photo-cured product. When the functionalgroup is attached to a mold surface, a thin film of thefluorine-containing surfactant (C) may be formed at the interfacebetween the mold and the resist and thereby decreases demolding force.In particular, when the terminal functional group has a high polarity,this probably facilitates the formation of a polar bond with the moldsurface and the formation of the thin film.

Furthermore, when the fluorine-containing surfactant (C) has aperfluoroalkyl chain (C-a) on one end and a polar functional group (C-c)on the other end, and the perfluoroalkyl chain is linked to the polarfunctional group through a poly(alkylene oxide) chain (C-b1) and/or analkyl chain (C-b2), it is surmised that the polar functional group (C-c)forms a polar bond with the mold surface, and a thin film of thefluorine-containing surfactant (C) formed at the interface between themold and the resist can decrease demolding force.

Specific examples of the perfluoroalkyl chain (C-a) include, but are notlimited to, fluorine-substituted linear alkyl groups having 1 to 20carbon atoms, such as a perfluoromethyl group, a perfluoroethyl group, aperfluoropropyl group, a perfluorobutyl group, a perfluoropentyl group,a perfluorohexyl group, a perfluoroheptyl group, a perfluorooctyl group,a perfluorononyl group, and a perfluorodecyl group. From theenvironmental safety point of view, the number of carbon atoms may beseven or less.

Specific examples of the polar functional group (C-c) include, but arenot limited to, alkylhydroxy groups, a carboxy group, a thiol group, anamino group, a pyridyl group, a silanol group, and a sulfo group.

Specific examples of the poly(alkylene oxide) chain (C-b1) include, butare not limited to, polyethylene oxide) chains having a repeating unitnumber in the range of 1 to 100 and poly(propylene oxide) chains havinga repeating unit number in the range of 1 to 100.

Specific examples of the alkyl chain (C-b2) include, but are not limitedto, alkyl groups having 1 to 100 carbon atoms and a linear or ringstructure.

The (C-a) and the (C-b1), the (C-a) and the (C-b2), the (C-b1) and the(C-c), or the (C-b2) and the (C-c) may be linked through a divalentlinking group. Specific examples of the divalent linking group include,but are not limited to, alkylene groups, a phenylene group, anaphthylene group, ester groups, ether groups, thioether groups, asulfonyl group, a secondary amino group, a tertiary amino group, anamide group, and a urethane group.

The fluorine-containing surfactant (C) may be at least one compoundhaving the following general formula (1):

[Chem. 1]

F(CF₂)₆(CH₂)_(m)(OCH₂CH₂)_(n)OH  (1)

wherein m is an integer in the range of 1 to 3, and n is an integer inthe range of 1 to 100.

The fluorine-containing surfactant (C) may be used alone or incombination.

The fluorine-containing surfactant (C) may constitute 0.001% by weightto 5% by weight, preferably 0.002% by weight to 4% by weight, morepreferably 0.005% by weight to 3% by weight, of the amount ofpolymerizable monomer (A). As described above, the amount offluorine-containing surfactant (C) is controlled such that a photo-curedproduct of a photo-curable composition according to an embodiment of thepresent invention has a water contact angle of 74 degrees or less.

The photo-cured product may have a water contact angle of 74 degrees orless and 1 degree or more, preferably 10 degrees or more.

In particular, the photo-cured product may have a water contact angle of70 degrees or less, or 71 degrees or more and 74 degrees or less.

Measurement of Water Contact Angle

A method for measuring the water contact angle of a photo-cured productaccording to the present invention will be described below.

A photo-cured product may be prepared by applying a photo-curablecomposition according to an embodiment of the present invention to asubstrate by coating, such as spin coating, and irradiating thephoto-curable composition with light in an inert atmosphere, such as anitrogen gas atmosphere, to form a photo-cured film.

The water contact angle may be measured with a commercially availablecontact angle meter, such as a fully-automatic contact angle meter CA-W(manufactured by Kyowa Interface Science Co., Ltd.).

The water contact angle of a photo-cured film in the present inventionis defined as the angle between a surface of the photo-cured film and atangent line at the intersection of 1 μl of pure water on thephoto-cured film and the photo-cured film. The water contact angle maybe the mean value of a plurality of measurements at different positionson a sample.

Polymerizable Monomer (A)

The polymerizable monomer of a photo-curable composition according to anembodiment of the present invention may be a radical-polymerizablemonomer or a cation-polymerizable monomer.

The radical-polymerizable monomer may be a compound having at least oneacryloyl or methacryloyl group. The cation-polymerizable monomer may bea compound having at least one vinyl ether group, epoxy group, oroxetanyl group.

Polymerizable Monomer (A): Radical-Polymerizable Component

Examples of a monofunctional (meth)acryl compound having one acryloyl ormethacryloyl group include, but are not limited to, phenoxyethyl(meth)acrylate, phenoxy-2-methylethyl (meth)acrylate, phenoxyethoxyethyl(meth)acrylate, 3-phenoxy-2-hydroxypropyl (meth)acrylate,2-phenylphenoxyethyl (meth)acrylate, 4-phenylphenoxyethyl(meth)acrylate, 3-(2-phenylphenyl)-2-hydroxypropyl (meth)acrylate,EO-modified p-cumylphenol (meth)acrylate, 2-bromophenoxyethyl(meth)acrylate, 2,4-dibromophenoxyethyl (meth)acrylate,2,4,6-tribromophenoxyethyl (meth)acrylate, EO-modified phenoxy(meth)acrylate, PO-modified phenoxy (meth)acrylate, polyoxyethylenenonylphenyl ether (meth)acrylate, isobornyl (meth)acrylate, 1-adamantyl(meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, 2-ethyl-2-adamantyl(meth)acrylate, bornyl (meth)acrylate, tricyclodecanyl (meth)acrylate,dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate,cyclohexyl (meth)acrylate, 4-butylcyclohexyl (meth)acrylate,acryloylmorpholine, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl(meth)acrylate, 2-hydroxybutyl (meth)acrylate, methyl (meth)acrylate,ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate,butyl (meth)acrylate, amyl (meth)acrylate, isobutyl (meth)acrylate,t-butyl (meth)acrylate, pentyl (meth)acrylate, isoamyl (meth)acrylate,hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate,isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl(meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl(meth)acrylate, dodecyl (meth)acrylate, lauryl (meth)acrylate, stearyl(meth)acrylate, isostearyl (meth)acrylate, benzyl (meth)acrylate,tetrahydrofurfuryl (meth)acrylate, butoxyethyl (meth)acrylate,ethoxydiethylene glycol (meth)acrylate, polyethylene glycol)mono(meth)acrylate, poly(propylene glycol) mono(meth)acrylate,methoxyethylene glycol (meth)acrylate, ethoxyethyl (meth)acrylate,methoxy polyethylene glycol) (meth)acrylate, methoxy poly(propyleneglycol) (meth)acrylate, diacetone(meth)acrylamide,isobutoxymethyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide,t-octyl(meth)acrylamide, dimethylaminoethyl (meth)acrylate,diethylaminoethyl (meth)acrylate, 7-amino-3,7-dimethyloctyl(meth)acrylate, N,N-diethyl(meth)acrylamide, andN,N-dimethylaminopropyl(meth)acrylamide.

The monofunctional (meth)acryl compound may be, but is not limited to,the following product: Aronix M101, M102, M110, M111, M113, M117, M5700,TO-1317, M120, M150, or M156 (manufactured by Toagosei Co., Ltd.), MEDOL10, MIBDOL 10, CHDOL 10, MMDOL 30, MEDOL 30, MIBDOL 30, CHDOL 30, LA,IBXA, 2-MTA, HPA, or Viscoat #150, #155, #158, #190, #192, #193, #220,#2000, #2100, or #2150 (manufactured by Osaka Organic Chemical IndustryLtd.), Light Acrylate BO-A, EC-A, DMP-A, THF-A, HOP-A, HOA-MPE, HOA-MPL,PO-A, P-200A, NP-4EA, or NP-8EA, or epoxy ester M-600A (manufactured byKyoeisha Chemical Co., Ltd.), Kayarad TC110S, R-564, or R-128H(manufactured by Nippon Kayaku Co., Ltd.), NK ester AMP-10G or AMP-20G(manufactured by Shin Nakamura Chemical Co., Ltd.), FA-511A, 512A, or513A (manufactured by Hitachi Chemical Co., Ltd.), PHE, CEA, PHE-2,PHE-4, BR-31, BR-31M, or BR-32 (manufactured by Dai-ichi Kogyo SeiyakuCo., Ltd.), VP (manufactured by BASF), or ACMO, DMAA, or DMAPAA(manufactured by Kohjin Co., Ltd.).

Examples of a polyfunctional (meth)acryl compound having at least twoacryloyl or methacryloyl groups include, but are not limited to,trimethylolpropane di(meth)acrylate, trimethylolpropanetri(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate,PO-modified trimethylolpropane tri(meth)acrylate, EO,PO-modifiedtrimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate,pentaerythritol tetra(meth)acrylate, ethylene glycol di(meth)acrylate,tetra(ethylene glycol) di(meth)acrylate, polyethylene glycol)di(meth)acrylate, poly(propylene glycol) di(meth)acrylate,1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate,neopentyl glycol di(meth)acrylate, tris(2-hydroxyethyl)isocyanuratetri(meth)acrylate, tris(acryloyloxy)isocyanurate,bis(hydroxymethyl)tricyclodecane di(meth)acrylate, dipentaerythritolpenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, EO-modified2,2-bis(4-((meth)acryloxy)phenyl)propane, PO-modified2,2-bis(4-((meth)acryloxy)phenyl)propane, and EO,PO-modified2,2-bis(4-((meth)acryloxy)phenyl)propane.

The polyfunctional (meth)acryl compound may be, but is not limited to,the following product: Yupimer UV SA1002 or SA2007 (manufactured byMitsubishi Chemical Corp.), Viscoat #195, #230, #215, #260, #335HP,#295, #300, #360, #700, GPT, or 3PA (manufactured by Osaka OrganicChemical Industry Ltd.), Light Acrylate 4EG-A, 9EG-A, NP-A, DCP-A,BP-4EA, BP-4PA, TMP-A, PE-3A, PE-4A, or DPE-6A (manufactured by KyoeishaChemical Co., Ltd.), Kayarad PET-30, TMPTA, R-604, DPHA, DPCA-20, -30,-60, or -120, HX-620, D-310, or D-330 (manufactured by Nippon KayakuCo., Ltd.), Aronix M208, M210, M215, M220, M240, M305, M309, M310, M315,M325, or M400 (manufactured by Toagosei Co., Ltd.), or Ripoxy VR-77,VR-60, or VR-90 (manufactured by Showa Highpolymer Co., Ltd.).

These radical-polymerizable monomers may be used alone or incombination. The term “(meth)acrylate”, as used herein, refers to anacrylate and its corresponding methacrylate. The term “(meth)acryloylgroup”, as used herein, refers to an acryloyl group and itscorresponding methacryloyl group. EO denotes ethylene oxide, and anEO-modified compound has a block structure of an ethylene oxide group.PO denotes propylene oxide, and a PO-modified compound has a blockstructure of a propylene oxide group.

Polymerizable Monomer (A): Cation-Polymerizable Component

Examples of a compound having one vinyl ether group include, but are notlimited to, methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether,n-butyl vinyl ether, t-butyl vinyl ether, 2-ethylhexyl vinyl ether,n-nonyl vinyl ether, lauryl vinyl ether, cyclohexyl vinyl ether,cyclohexylmethyl vinyl ether, 4-methylcyclohexylmethyl vinyl ether,benzyl vinyl ether, dicyclopentenyl vinyl ether, 2-dicyclopentenoxyethylvinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether,butoxyethyl vinyl ether, methoxyethoxyethyl vinyl ether,ethoxyethoxyethyl vinyl ether, methoxy poly(ethylene glycol) vinylether, tetrahydrofurfuryl vinyl ether, 2-hydroxyethyl vinyl ether,2-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether,4-hydroxymethylcyclohexylmethyl vinyl ether, diethylene glycol monovinylether, poly(ethylene glycol) vinyl ether, chloroethyl vinyl ether,chlorobutyl vinyl ether, chloroethoxyethyl vinyl ether, phenylethylvinyl ether, and phenoxy poly(ethylene glycol) vinyl ether.

Examples of a compound having at least two vinyl ether groups include,but are not limited to, divinyl ethers, such as ethylene glycol divinylether, diethylene glycol divinyl ether, poly(ethylene glycol) divinylether, propylene glycol divinyl ether, butylene glycol divinyl ether,hexanediol divinyl ether, bisphenol A alkylene oxide divinyl ethers, andbisphenol F alkylene oxide divinyl ethers; and polyfunctional vinylethers, such as trimethylolethane trivinyl ether, trimethylolpropanetrivinyl ether, ditrimethylolpropane tetravinyl ether, glycerin trivinylether, pentaerythritol tetravinyl ether, dipentaerythritol pentavinylether, dipentaerythritol hexavinyl ether, ethylene oxide adducts oftrimethylolpropane trivinyl ether, propylene oxide adducts oftrimethylolpropane trivinyl ether, ethylene oxide adducts ofditrimethylolpropane tetravinyl ether, propylene oxide adducts ofditrimethylolpropane tetravinyl ether, ethylene oxide adducts ofpentaerythritol tetravinyl ether, propylene oxide adducts ofpentaerythritol tetravinyl ether, ethylene oxide adducts ofdipentaerythritol hexavinyl ether, and propylene oxide adducts ofdipentaerythritol hexavinyl ether.

Examples of a compound having one epoxy group include, but are notlimited to, phenyl glycidyl ether, p-tert-butylphenyl glycidyl ether,butyl glycidyl ether, 2-ethylhexyl glycidyl ether, allyl glycidyl ether,1,2-butylene oxide, 1,3-butadiene monoxide, 1,2-epoxidedecane,epichlorohydrin, 1,2-epoxydecane, styrene oxide, cyclohexene oxide,3-methacryloyloxymethylcyclohexene oxide, 3-acryloyloxymethylcyclohexeneoxide, and 3-vinylcyclohexene oxide.

Examples of a compound having at least two epoxy groups include, but arenot limited to, bisphenol A diglycidyl ether, bisphenol F diglycidylether, bisphenol S diglycidyl ether, brominated bisphenol A diglycidylether, brominated bisphenol F diglycidyl ether, brominated bisphenol Sdiglycidyl ether, epoxy novolak resin, hydrogenated bisphenol Adiglycidyl ether, hydrogenated bisphenol F diglycidyl ether,hydrogenated bisphenol S diglycidyl ether,3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexane carboxylate,2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)cyclohexane-meta-dioxane,bis(3,4-epoxycyclohexylmethyl)adipate, vinylcyclohexene oxide,4-vinylepoxycyclohexane, bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate,3,4-epoxy-6-methylcyclohexyl-3′,4′-epoxy-6′-methylcyclohexanecarboxylate, methylene bis(3,4-epoxycyclohexane), dicyclopentadienediepoxide, ethylene glycol di(3,4-epoxycyclohexylmethyl)ether, ethylenebis(3,4-epoxycyclohexane carboxylate), epoxyhexahydrodioctyl phthalate,epoxyhexahydrodi-2-ethylhexyl phthalate, 1,4-butanediol diglycidylether, 1,6-hexanediol diglycidyl ether, glycerin triglycidyl ether,trimethylolpropane triglycidyl ether, polyethylene glycol) diglycidylether, poly(propylene glycol) diglycidyl ether, 1,1,3-tetradecadienedioxide, limonene dioxide, 1,2,7,8-diepoxyoctane, and1,2,5,6-diepoxycyclooctane.

Examples of a compound having one oxetanyl group include, but are notlimited to, 3-ethyl-3-hydroxymethyloxetane,3-(meta)allyloxymethyl-3-ethyloxetane,(3-ethyl-3-oxetanylmethoxy)methylbenzene,4-fluoro-[1-(3-ethyl-3-oxetanylmethoxy)methyl]benzene,4-methoxy-[1-(3-ethyl-3-oxetanylmethoxy)methyl]benzene,[1-(3-ethyl-3-oxetanylmethoxy)ethyl]phenyl ether, isobutoxymethyl(3-ethyl-3-oxetanylmethyl)ether, isobornyloxyethyl(3-ethyl-3-oxetanylmethyl)ether, isobornyl(3-ethyl-3-oxetanylmethyl)ether, 2-ethylhexyl(3-ethyl-3-oxetanylmethyl)ether, ethyldiethylene glycol(3-ethyl-3-oxetanylmethyl)ether, dicyclopentadiene(3-ethyl-3-oxetanylmethyl)ether, dicyclopentenyloxyethyl(3-ethyl-3-oxetanylmethyl)ether, dicyclopentenyl(3-ethyl-3-oxetanylmethyl)ether, tetrahydrofurfuryl(3-ethyl-3-oxetanylmethyl)ether, tetrabromophenyl(3-ethyl-3-oxetanylmethyl)ether, 2-tetrabromophenoxyethyl(3-ethyl-3-oxetanylmethyl)ether, tribromophenyl(3-ethyl-3-oxetanylmethyl)ether, 2-tribromophenoxyethyl(3-ethyl-3-oxetanylmethyl)ether, 2-hydroxyethyl(3-ethyl-3-oxetanylmethyl)ether, 2-hydroxypropyl(3-ethyl-3-oxetanylmethyl)ether, butoxyethyl(3-ethyl-3-oxetanylmethyl)ether, pentachlorophenyl(3-ethyl-3-oxetanylmethyl)ether, pentabromophenyl(3-ethyl-3-oxetanylmethyl)ether, and bornyl(3-ethyl-3-oxetanylmethyl)ether.

Examples of a compound having at least two oxetanyl groups include, butare not limited to, polyfunctional oxetanes, such as3,7-bis(3-oxetanyl)-5-oxa-nonane, 3,3′-(1,3-(2-methylenyl)propanediylbis(oxymethylene))bis-(3-ethyloxetane),1,4-bis[(3-ethyl-3-oxetanylmethoxy)methyl]benzene,1,2-bis[(3-ethyl-3-oxetanylmethoxy)methyl]ethane,1,3-bis[(3-ethyl-3-oxetanylmethoxy)methyl]propane, ethylene glycolbis(3-ethyl-3-oxetanylmethyl)ether, dicyclopentenylbis(3-ethyl-3-oxetanylmethyl)ether, tri(ethylene glycol)bis(3-ethyl-3-oxetanylmethyl)ether, tetra(ethylene glycol)bis(3-ethyl-3-oxetanylmethyl)ether, tricyclodecanediyldimethylene(3-ethyl-3-oxetanylmethyl)ether, trimethylolpropanetris(3-ethyl-3-oxetanylmethyl)ether,1,4-bis(3-ethyl-3-oxetanylmethoxy)butane,1,6-bis(3-ethyl-3-oxetanylmethoxy)hexane, pentaerythritoltris(3-ethyl-3-oxetanylmethyl)ether, pentaerythritoltetrakis(3-ethyl-3-oxetanylmethyl)ether, polyethylene glycol)bis(3-ethyl-3-oxetanylmethyl)ether, dipentaerythritolhexakis(3-ethyl-3-oxetanylmethyl)ether, dipentaerythritolpentakis(3-ethyl-3-oxetanylmethyl)ether, dipentaerythritoltetrakis(3-ethyl-3-oxetanylmethyl)ether, caprolactone-modifieddipentaerythritol hexakis(3-ethyl-3-oxetanylmethyl)ether,caprolactone-modified dipentaerythritolpentakis(3-ethyl-3-oxetanylmethyl)ether, ditrimethylolpropanetetrakis(3-ethyl-3-oxetanylmethyl)ether, EO-modified bisphenol Abis(3-ethyl-3-oxetanylmethyl)ether, PO-modified bisphenol Abis(3-ethyl-3-oxetanylmethyl)ether, EO-modified hydrogenated bisphenol Abis(3-ethyl-3-oxetanylmethyl)ether, PO-modified hydrogenated bisphenol Abis(3-ethyl-3-oxetanylmethyl)ether, and EO-modified bisphenol F(3-ethyl-3-oxetanylmethyl)ether.

These cation-polymerizable monomers may be used alone or in combination.EO denotes ethylene oxide, and an EO-modified compound has a blockstructure of an ethylene oxide group. PO denotes propylene oxide, and aPO-modified compound has a block structure of a propylene oxide group.The term “hydrogenated”, as used herein, refers to the addition ofhydrogen atoms to a C═C double bond, for example, of a benzene ring.

Polymerization Initiator (B)

When the polymerizable monomer (A) is a radical-polymerizable monomer,the polymerization initiator (B) generates a radical by the action oflight (infrared rays, visible light, ultraviolet light, far-ultravioletlight, X-rays, charged particle beams, such as an electron beam, orradioactive rays). When the polymerizable monomer (A) is acation-polymerizable monomer, the polymerization initiator (B) generatesan acid by the action of light.

Examples of the radical generator include, but are not limited to,

optionally substituted 2,4,5-triarylimidazole dimers, such as2-(o-chlorophenyl)-4,5-diphenylimidazole dimer,2-(o-chlorophenyl)-4,5-di(methoxyphenyl)imidazole dimer,2-(o-fluorophenyl)-4,5-diphenylimidazole dimer, and 2-(o- orp-methoxyphenyl)-4,5-diphenylimidazole dimer;

benzophenone and benzophenone derivatives, such asN,N′-tetramethyl-4,4′-diaminobenzophenone (Michler's ketone),N,N′-tetraethyl-4,4′-diaminobenzophenone,4-methoxy-4′-dimethylaminobenzophenone, 4-chlorobenzophenone,4,4′-dimethoxybenzophenone, and 4,4′-diaminobenzophenone;

aromatic ketone derivatives, such as2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1,2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propanon-1-one;

quinones, such as 2-ethylanthraquinone, phenanthrenequinone,2-t-butylanthraquinone, octamethylanthraquinone, 1,2-benzanthraquinone,2,3-benzanthraquinone, 2-phenylanthraquinone, 2,3-diphenylanthraquinone,1-chloroanthraquinone, 2-methylanthraquinone, 1,4-naphthoquinone,9,10-phenanthrenequinone, 2-methyl-1,4-naphthoquinone, and2,3-dimethylanthraquinone;

benzoin ether derivatives, such as benzoin methyl ether, benzoin ethylether, and benzoin phenyl ether;

benzoin and benzoin derivatives, such as methylbenzoin, ethylbenzoin,and propylbenzoin;

benzyl derivatives, such as benzyl dimethyl ketal;

acridine derivatives, such as 9-phenylacridine and1,7-bis(9,9′-acridinyl)heptane;

N-phenylglycine and N-phenylglycine derivatives;

acetophenone and acetophenone derivatives, such as 3-methylacetophenone,acetophenone benzyl ketal, 1-hydroxycyclohexyl phenyl ketone, and2,2-dimethoxy-2-phenylacetophenone;

thioxanthone and thioxanthone derivatives, such as diethylthioxanthone,2-isopropylthioxanthone, and 2-chlorothioxanthone;

xanthone, fluorenone, benzaldehyde, fluorene, anthraquinone,triphenylamine, carbazole,1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, and2-hydroxy-2-methyl-1-phenylpropan-1-one; and

2,4,6-trimethylbenzoyldiphenylphosphine oxide, andbis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide. Theseradical generators may be used alone or in combination.

The photo-induced radical generator may be, but is not limited to, thefollowing product: Irgacure 184, 369, 651, 500, 819, 907, 784, 2959,CGI-1700, -1750, or -1850, or CG24-61, or Darocur 1116 or 1173(manufactured by Ciba Japan K.K.), Lucirin TPO, LR8893, or LR8970(manufactured by BASF), or Ebecryl P36 (manufactured by UCB).

Examples of a compound used as a polymerization initiator that producesan acid by the action of light include, but are not limited to, oniumsalt compounds, sulfone compounds, sulfonate ester compounds,sulfonimide compounds, and diazomethane compounds.

Examples of the onium salt compounds include, but are not limited to,iodonium salts, sulfonium salts, phosphonium salts, diazonium salts,ammonium salts, and pyridinium salts. Specific examples of the oniumsalt compounds include, but are not limited to,bis(4-t-butylphenyl)iodonium perfluoro-n-butane sulfonate,bis(4-t-butylphenyl)iodonium trifluoromethane sulfonate,bis(4-t-butylphenyl)iodonium 2-trifluoromethylbenzene sulfonate,bis(4-t-butylphenyl)iodonium pyrene sulfonate,bis(4-t-butylphenyl)iodonium n-dodecylbenzene sulfonate,bis(4-t-butylphenyl)iodonium p-toluene sulfonate,bis(4-t-butylphenyl)iodonium benzene sulfonate,bis(4-t-butylphenyl)iodonium 10-camphorsulfonate,bis(4-t-butylphenyl)iodonium n-octane sulfonate, diphenyliodoniumperfluoro-n-butane sulfonate, diphenyliodonium trifluoromethanesulfonate, diphenyliodonium 2-trifluoromethylbenzene sulfonate,diphenyliodonium pyrene sulfonate, diphenyliodonium n-dodecylbenzenesulfonate, diphenyliodonium p-toluene sulfonate, diphenyliodoniumbenzene sulfonate, diphenyliodonium 10-camphorsulfonate,diphenyliodonium n-octane sulfonate, triphenylsulfoniumperfluoro-n-butane sulfonate, triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium 2-trifluoromethylbenzene sulfonate,triphenylsulfonium pyrene sulfonate, triphenylsulfonium n-dodecylbenzenesulfonate, triphenylsulfonium p-toluene sulfonate, triphenylsulfoniumbenzene sulfonate, triphenylsulfonium 10-camphorsulfonate,triphenylsulfonium n-octane sulfonate,diphenyl(4-t-butylphenyl)sulfonium perfluoro-n-butane sulfonate,diphenyl(4-t-butylphenyl)sulfonium trifluoromethane sulfonate,diphenyl(4-t-butylphenyl)sulfonium 2-trifluoromethylbenzene sulfonate,diphenyl(4-t-butylphenyl)sulfonium pyrene sulfonate,diphenyl(4-t-butylphenyl)sulfonium n-dodecylbenzene sulfonate,diphenyl(4-t-butylphenyl)sulfonium p-toluene sulfonate,diphenyl(4-t-butylphenyl)sulfonium benzene sulfonate,diphenyl(4-t-butylphenyl)sulfonium 10-camphorsulfonate,diphenyl(4-t-butylphenyl)sulfonium n-octane sulfonate,tris(4-methoxyphenyl)sulfonium perfluoro-n-butane sulfonate,tris(4-methoxyphenyl)sulfonium trifluoromethane sulfonate,tris(4-methoxyphenyl)sulfonium 2-trifluoromethylbenzene sulfonate,tris(4-methoxyphenyl)sulfonium pyrene sulfonate,tris(4-methoxyphenyl)sulfonium n-dodecylbenzene sulfonate,tris(4-methoxyphenyl)sulfonium p-toluene sulfonate,tris(4-methoxyphenyl)sulfonium benzene sulfonate,tris(4-methoxyphenyl)sulfonium 10-camphorsulfonate, andtris(4-methoxyphenyl)sulfonium n-octane sulfonate.

Examples of the sulfone compounds include, but are not limited to,β-ketosulfones, β-sulfonylsulfones, and α-diazo compounds thereof.Specific examples of the sulfone compounds include, but are not limitedto, phenacyl phenyl sulfone, mesityl phenacyl sulfone,bis(phenylsulfonyl)methane, and 4-trisphenacyl sulfone.

Examples of the sulfonate ester compounds include, but are not limitedto, alkyl sulfonate esters, haloalkyl sulfonate esters, aryl sulfonateesters, and iminosulfonates. Specific examples of the sulfonate estercompounds include, but are not limited to, α-methylolbenzoinperfluoro-n-butane sulfonate, α-methylolbenzoin trifluoromethanesulfonate, and a-methylolbenzoin 2-trifluoromethylbenzene sulfonate.

Specific example of the sulfonimide compounds include, but are notlimited to, N-(trifluoromethylsulfonyloxy)succinimide,N-(trifluoromethylsulfonyloxy)phthalimide,N-(trifluoromethylsulfonyloxy)diphenylmaleimide,N-(trifluoromethylsulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylmide,N-(trifluoromethylsulfonyloxy)-7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboxylmide,N-(trifluoromethylsulfonyloxy)bicyclo[2.2.1]heptan-5,6-oxy-2,3-dicarboxylmide,N-(trifluoromethylsulfonyloxy)naphthylimide,N-(10-camphorsulfonyloxy)succinimide,N-(10-camphorsulfonyloxy)phthalimide,N-(10-camphorsulfonyloxy)diphenylmaleimide,N-(10-camphorsulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylmide,N-(10-camphorsulfonyloxy)-7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboxylmide,N-(10-camphorsulfonyloxy)bicyclo[2.2.1]heptan-5,6-oxy-2,3-dicarboxylmide,N-(10-camphorsulfonyloxy)naphthylimide,N-(4-methylphenylsulfonyloxy)succinimide,N-(4-methylphenylsulfonyloxy)phthalimide,N-(4-methylphenylsulfonyloxy)diphenylmaleimide,N-(4-methylphenylsulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylmide,N-(4-methylphenylsulfonyloxy)-7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboxylmide,N-(4-methylphenylsulfonyloxy)bicyclo[2.2.1]heptan-5,6-oxy-2,3-dicarboxylmide,N-(4-methylphenylsulfonyloxy)naphthylimide,N-(2-trifluoromethylphenylsulfonyloxy)succinimide,N-(2-trifluoromethylphenylsulfonyloxy)phthalimide,N-(2-trifluoromethylphenylsulfonyloxy)diphenylmaleimide,N-(2-trifluoromethylphenylsulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylmide,N-(2-trifluoromethylphenylsulfonyloxy)-7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboxylmide,N-(2-trifluoromethylphenylsulfonyloxy)bicyclo[2.2.1]heptan-5,6-oxy-2,3-dicarboxylmide,N-(2-trifluoromethylphenylsulfonyloxy)naphthylimide,N-(4-fluorophenylsulfonyloxy)succinimide, N-(4-fluorophenyl)phthalimide,N-(4-fluorophenylsulfonyloxy)diphenylmaleimide,N-(4-fluorophenylsulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylmide,N-(4-fluorophenylsulfonyloxy)-7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboxylmide,N-(4-fluorophenylsulfonyloxy)bicyclo[2.2.1]heptan-5,6-oxy-2,3-dicarboxylmide,and N-(4-fluorophenylsulfonyloxy)naphthylimide.

Specific examples of the diazomethane compounds include, but are notlimited to, bis(trifluoromethylsulfonyl)diazomethane,bis(cyclohexylsulfonyl)diazomethane, bis(phenylsulfonyl)diazomethane,bis(p-toluenesulfonyl)diazomethane, methylsulfonylp-toluenesulfonyldiazomethane,(cyclohexylsulfonyl)(1,1-dimethylethylsulfonyl)diazomethane, andbis(1,1-dimethylethylsulfonyl)diazomethane.

These acid generators may be used alone or in combination.

The polymerization initiator (B) component constitutes 0.01% by weightor more and 10% by weight or less, preferably 0.1% by weight or more and7% by weight or less, of the amount of polymerizable monomer (A). Lessthan 0.01% by weight may result in a decreased curing rate and lowreaction efficiency. On the other hand, more than 10% by weight mayresult in poor mechanical characteristics of a cured product of thephoto-curable composition.

Other Additive Components

In addition to the polymerizable monomer (A), the polymerizationinitiator (B), and the fluorine-containing surfactant (C), aphoto-curable composition according to an embodiment of the presentinvention may contain other additive components, such as a sensitizer,an antioxidant, a solvent, and/or a polymer component, for each purposewithout losing the advantages of the present invention.

The sensitizer can promote polymerization reaction and improve reactionconversion. The sensitizer may be a hydrogen donor or a sensitizing dye.

The hydrogen donor can react with an initiator radical generated fromthe polymerization initiator (B) or a propagating radical to form a morereactive radical. The hydrogen donor can be added when thepolymerization initiator (B) is a photo-induced radical generator.

Specific examples of the hydrogen donor include, but are not limited to,amine compounds, such as N-butylamine, di-n-butylamine,tri-n-butylphosphine, allylthiourea, s-benzylisothiuronium-p-toluenesulfinate, triethylamine, dimethylaminoethyl methacrylate,triethylenetetramine, 4,4′-bis(dialkylamino)benzophenone, ethylN,N-dimethylaminobenzoate, isoamyl N,N-dimethylaminobenzoate,pentyl-4-dimethylaminobenzoate, triethanolamine, and N-phenylglycine;and mercapto compounds, such as 2-mercapto-N-phenylbenzoimidazole andmercaptopropionate.

The sensitizing dye is excited by absorbing light having a particularwavelength and acts on the polymerization initiator (B). The term “acton”, as used herein, refers to energy transfer or electron transfer fromthe excited sensitizing dye to the polymerization initiator (B).

Specific examples of the sensitizing dye include, but are not limitedto, anthracene derivatives, anthraquinone derivatives, pyrenederivatives, perylene derivatives, carbazole derivatives, benzophenonederivatives, thioxanthone derivatives, xanthone derivatives,thioxanthone derivatives, coumarin derivatives, phenothiazinederivatives, camphorquinone derivatives, acridine dyes, thiopyryliumsalt dyes, merocyanine dyes, quinoline dyes, styrylquinoline dyes,ketocoumarin dyes, thioxanthene dyes, xanthene dyes, oxonol dyes,cyanine dyes, rhodamine dyes, and pyrylium salt dyes.

The sensitizer may be used alone or in combination.

The sensitizer in a photo-curable composition according to an embodimentof the present invention preferably constitutes 0% to 20% by weight,more preferably 0.1% by weight to 5.0% by weight, still more preferably0.2% by weight to 2.0% by weight, of the amount of polymerizable monomer(A). When the sensitizer content is 0.1% by weight or more, the effectsof the sensitizer can be more effectively produced. When the sensitizercontent is 5.0% by weight or less, a photo-cured product can have asufficiently high molecular weight, and deterioration in solubility orstorage stability can be prevented.

Temperature of Photo-Curable Composition in Blending

A photo-curable composition may be mixed and dissolved at a temperaturein the range of 0° C. to 100° C.

Viscosity of Photo-Curable Composition

A photo-curable composition according to an embodiment of the presentinvention preferably has a viscosity in the range of 1 to 100 cP, morepreferably 5 to 50 cP, still more preferably 6 to 20 cP, at 23° C. inthe absence of solvent. A viscosity of more than 100 cP may result in along filling time of the composition in a micropatterned depressedportion on a mold or patterning defects because of insufficient fillingin a stamping step described below. A viscosity of less than 1 cP mayresult in uneven coating in a coating step described below or theoutflow of the composition from a mold in the stamping step describedbelow.

Surface Tension of Photo-Curable Composition

A photo-curable composition according to an embodiment of the presentinvention preferably has a surface tension in the range of 5 to 70 mN/m,more preferably 7 to 35 mN/m, still more preferably 10 to 32 mN/m, at23° C. in the absence of solvent.

A surface tension of less than 5 mN/m results in a long filling time ofthe composition in recessed and raised portions on a mold in a contactstep described below. A surface tension of more than 70 mN/m results inpoor surface smoothness.

Particulate Contaminant in Photo-Curable Composition

In order to prevent defects in recessed and raised portions of a curedproduct of the polymerizable monomer (A) caused by particulatecontaminants, after the components are mixed, a photo-curablecomposition may be passed through a filter having a pore size in therange of 0.001 to 5.0 μm. The filtration may be performed in multiplesteps or multiple times. A filtered liquid may be filtered again. Thematerial of the filter may be, but is not limited to, polyethyleneresin, polypropylene resin, fluoropolymer, or nylon resin.

Metal Impurities in Photo-Curable Composition

Metal impurities in a photo-curable composition for use in themanufacture of semiconductor integrated circuits are minimized so as notto inhibit the operation of the circuits. Thus, the concentration ofmetal impurities in a photo-curable composition according to anembodiment of the present invention is preferably 10 ppm or less, morepreferably 100 ppb or less.

Patterning Method

A patterning method according to an embodiment of the present inventioninvolves a placing step of placing a photo-curable composition on asubstrate to be processed (FIG. 1A), a mold contact step of bringing thephoto-curable composition into contact with a mold (FIG. 1B), aphotoirradiation step of irradiating the photo-curable composition withlight while the photo-curable composition is in contact with the mold(FIG. 1C), and a demolding step of releasing the photo-curablecomposition from the mold (FIG. 1D).

In the photoirradiation step, the photo-curable composition may beirradiated with light through the mold.

The method may further involve an exposure step of etching part of afilm of the photo-curable composition remaining in depressed portionsafter the demolding step to expose a surface of the substrate in thedepressed portions (FIG. 1E).

Each of the steps of a patterning method according to the presentinvention will be described below.

Placing Step (FIG. 1A)

In the present embodiment, the placing step of placing a photo-curablecomposition on a substrate to be processed is a coating step. Aphoto-curable composition according to an embodiment of the presentinvention is applied to a substrate to be processed.

The substrate to be processed may be a substrate, such as a siliconwafer. The substrate to be processed may also be a substrate forsemiconductor devices made of aluminum, a titanium-tungsten alloy, analuminum-silicon alloy, an aluminum-copper-silicon alloy, silicon oxide,or silicon nitride. The substrate to be processed may be a substratesubjected to surface treatment, such as silane coupling treatment,silazane treatment, or the formation of an organic film, to improveadhesion to the photo-curable composition.

The photo-curable composition may be applied by an ink jet method, a dipcoating method, an air knife coating method, a curtain coating method, awire bar coating method, a gravure coating method, an extrusion coatingmethod, a spin coating method, or a slit scanning method. The filmthickness of the photo-curable composition depends on the applicationand is in the range of 0.01 to 100.0 μm, for example.

Mold Contact Step (FIG. 1B)

In the mold contact step of bringing the photo-curable composition intocontact with a mold, recessed and raised portions (micropattern) on asurface of the mold are filled with the photo-curable composition.

The mold is made of an optically transparent material, for example,glass, quartz, an optically transparent resin, such as PMMA orpolycarbonate resin, a transparent metallized film, a soft film, such asa polydimethylsiloxane film, a photo-cured film, or a metal film.

A surface of the mold in contact with the photo-curable composition maybe hydrophilic so as to facilitate the formation of a polar bond withthe fluorine-containing surfactant (C).

A mold for use in a patterning method according to an embodiment of thepresent invention may be subjected to surface treatment so as to improvethe releasability of a photo-curable composition from the mold. Thesurface treatment may involve the use of a silane coupling agent, suchas a silicone or fluorinated coupling agent, for example, a commerciallyavailable coating-type mold-release agent, such as Optool DSXmanufactured by Daikin Industries, Ltd.

The contact pressure is generally, but not limited to, in the range of0.1 Pa to 100 MPa, preferably 0.1 Pa to 50 MPa, more preferably 0.1 Pato 30 MPa, still more preferably 0.1 Pa to 20 MPa. The contact time isgenerally, but not limited to, in the range of 1 to 600 seconds,preferably 1 to 300 seconds, more preferably 1 to 180 seconds, stillmore preferably 1 to 120 seconds.

A patterning method according to an embodiment of the present inventionmay be performed in the atmosphere, under reduced pressure, or in aninert gas atmosphere. Specific examples of inert gas include, but arenot limited to, nitrogen, carbon dioxide, helium, argon, variouschlorofluorocarbons, and mixtures thereof. The pressure may be in therange of 0.0001 to 10 atm. Use of reduced pressure or an inert gasatmosphere can eliminate the effects of oxygen or water on thephoto-curing reaction.

Photoirradiation Step (FIG. 1C)

In the photoirradiation step, the photo-curable composition isirradiated with light while the photo-curable composition is in contactwith the mold. In this step, the photo-curable composition in recessedand raised portions on the mold surface is cured.

The light is not particularly limited, depends on the sensitivewavelength of a photo-curable composition according to an embodiment ofthe present invention, and may be ultraviolet light having a wavelengthin the range of approximately 150 to 400 nm, X-rays, or an electron beamVarious photosensitive compounds sensitive to ultraviolet light areeasily available as the polymerization initiator (B). Examples ofultraviolet light sources include, but are not limited to, high-pressuremercury lamps, ultrahigh-pressure mercury lamps, low-pressure mercurylamps, deep-UV lamps, carbon arc lamps, chemical lamps, metal halidelamps, xenon lamps, KrF excimer lasers, ArF excimer lasers, and F₂excimer lasers. These light sources may be used alone or in combination.The photo-curable composition may be entirely or partly irradiated withlight.

If possible, the photo-curable composition may further be cured withheat. The heating atmosphere and the heating temperature of heat curingare not particularly limited and may be an inert atmosphere or underreduced pressure and in the range of 40° C. to 200° C. Heating may beperformed with a hot plate, an oven, or a furnace.

Demolding Step (FIG. 1D)

In the demolding step, the photo-curable composition is removed from themold. In this step, the reverse pattern of the recessed and raisedportions on the mold surface is transferred to a cured product of thephoto-curable composition.

The demolding method is not particularly limited, and various conditionsare also not particularly limited. For example, a substrate to beprocessed may be fixed while a mold may be moved away from the substrateto be processed, or a mold may be fixed while a substrate to beprocessed may be moved away from the mold, or a substrate to beprocessed and a mold may be moved in the opposite directions.

A patterning method according to an embodiment of the present inventionmay involve the use of a coating-type mold-release agent. Morespecifically, a coating-type mold-release agent layer may be formed on apatterned surface of a mold before the stamping step.

Examples of the coating-type mold-release agent include, but are notlimited to, silicon mold-release agents, fluorinated mold-releaseagents, polyethylene mold-release agents, polypropylene mold-releaseagents, paraffinic mold-release agents, montan mold-release agents, andcarnauba mold-release agents. The mold-release agent may be used aloneor in combination.

Exposure Step (FIG. 1E)

In the exposure step, part of a film of the photo-curable compositionremaining in depressed portions is etched to expose a surface of thesubstrate in the depressed portions.

The etching method is not particularly limited and may be a conventionalmethod, such as dry etching. A known dry etching apparatus may be usedin dry etching. The source gas for dry etching depends on the elementarycomposition of a film to be etched and may be an oxygen-containing gas,such as O₂, CO, or CO₂, an inert gas, such as He, N₂, or Ar, a chlorinegas, such as Cl₂ or BCl₃, H₂, or NH₃. These source gases may be usedalone or in combination.

Substrate Processing Step (FIG. 1F)

A pattern formed in the exposure step can be used as a film for aninterlayer insulating film of a semiconductor element, such as LSI,system LSI, DRAM, SDRAM, RDRAM, or D-RDRAM, or a resist film in themanufacture of a semiconductor element.

More specifically, as illustrated in FIG. 1F, the exposed portions inthe exposure step may be subjected to etching or ion implantation toform a circuit structure based on the photo-curable composition patternon the substrate to be processed. A circuit board for a semiconductorelement can be manufactured through these steps.

The photo-curable composition pattern may be removed from the substrateor may be left as a member for constituting the element.

The substrate may be used as an optical element having a texturedpattern on its surface. More specifically, the substrate may be providedas an article that includes a substrate and a cured product of thephoto-curable composition on the substrate.

EXAMPLES

The present invention will be further described in the followingexamples. However, the technical scope of the present invention is notlimited to these examples. Unless otherwise specified, “part” and “%”are based on weight.

Synthesis Example 1 Synthesis of Fluorine-Containing Surfactant (C-1)

A 300-mL reactor was charged with hexa(ethylene glycol) (PEG6) (26.5 g,93.9 mmol, 1.0 eq.), carbon tetrachloride (CCl₄) (36.1 g, 235 mmol, 2.5eq.), and tetrahydrofuran (THF) (106 mL) in a nitrogen atmosphere andwas cooled to −30° C. To this solution was slowly addeddimethylaminophosphine (15.3 g, 93.9 mmol, 1.0 eq.) diluted with THF (24mL) for two hours. After stirring for 30 minutes at that temperature, acooling bath was removed, and the solution was stirred at roomtemperature for two hours. To this pale yellow suspension was added citywater (250 mL) to separate the suspension into two layers (CCl₄ andaqueous layer). The aqueous layer was washed with isopropyl ether (IPE)(150 mL×2). Potassium hexafluorophosphate (KPF₆) (34.5 g, 188 mmol, 2.0eq.) dispersed in city water (250 mL) in this solution was added to theaqueous layer and was sufficiently stirred. An organic layer extractedwith dichloromethane (200 mL×3) was washed with city water (400 mL) andsaturated saline (300 mL) and was dried over anhydrous magnesiumsulfate. The solution was concentrated to yield a light brown liquid(C-1-a) (53 g).

A 500-mL reactor was charged with 1H,1H-perfluoro-1-heptanol (34.2 g,97.7 mmol, 1.2 eq.) and THF (120 mL). To this solution was slowly addedNaH (60%) (3.9 g, 97.7 mmol, 1.2 eq.) with attention to foaming. Afterstirring at 50° C. for one hour, the solvent was evaporated underreduced pressure. The liquid (C-1-a) (53 g) dissolved in anhydrousdioxane (600 mL) was added to the residue and was stirred at 60° C. for48 hours. The suspension was concentrated, and city water (300 mL) andethyl acetate (300 mL) were added to the resulting residue to separatethe residue into two layers. An aqueous layer was extracted with ethylacetate (200 mL×2). An organic layer was washed with city water (400 mL)and saturated saline (400 mL) and was dried over anhydrous magnesiumsulfate. The solution was concentrated to yield a brown liquid (59.1 g).The brown liquid was subjected to column purification (SiO₂: 1.2 kg,ethyl acetate alone=>ethyl acetate/methanol=10/1) and then columnpurification (SiO₂: 400 g, chloroform/methanol=15/1=>10/1) and was driedunder high vacuum to yield a fluorine-containing surfactant (C-1),hexa(ethylene glycol) mono-1H,1H-perfluoroheptyl ether(F(CF₂)₆CH₂(OCH₂CH₂)₆OH, 19.2 g, 31.2 mmol, yield 33%), as a colorlessliquid.

Example 1

A mixed solution was prepared by using 100 parts by weight of1,6-hexanediol diacrylate (manufactured by Osaka Organic ChemicalIndustry Ltd.) as the (A) component, 3 parts by weight of Irgacure 369(manufactured by Ciba Japan K.K.) as the (B) component, and 0.125 partsby weight of the fluorine-containing surfactant (C-1) as the (C)component. The mixed solution was passed through a 0.2 μmtetrafluoroethylene filter to yield a photo-curable composition (a-1)according to Example 1.

The surface tension of the photo-curable composition (a-1) was 31.5 mN/mas measured with an automatic surface tensiometer CBVP-A3 (manufacturedby Kyowa Interface Science Co., Ltd.).

The viscosity of the photo-curable composition (a-1) was 6.4 cP asmeasured with a cone-and-plate viscometer RE-85L (manufactured by TokiSangyo Co., Ltd.).

Measurement of Water Contact Angle

A film of the photo-curable composition (a-1) having a thickness ofapproximately 1 μm was formed on a silicon wafer by a spin coatingmethod.

A photo-cured film was prepared by irradiating the film of thephoto-curable composition (a-1) with light from a UV light source EX250(manufactured by Hoya Candeo Optronics Corp.) equipped with a 250-Wultrahigh-pressure mercury lamp in a nitrogen atmosphere through aninterference filter VPF-50C-10-25-36500 (manufactured by Sigmakoki Co.,Ltd.). The illuminance on the film was 25 mW/cm at a wavelength of 365nm. The photoirradiation time was 100 seconds.

The contact angle of 1 μl of pure water on the photo-cured film of thephoto-curable composition (a-1) was 69 degrees as measured with afully-automatic contact angle meter CA-W (manufactured by KyowaInterface Science Co., Ltd.).

Measurement of Demolding Force

15 μl of (a-1) was dropped with a micropipette on a 4-inch silicon waferthat has an adhesion-promoting layer having a thickness of 60 nm as anadhesion layer.

A 40×40 mm quartz mold having no surface treatment and no pattern wasstamped onto the silicon wafer.

An UV light source EXECURE 3000 (manufactured by Hoya Candeo OptronicsCorp.) equipped with a 200-W mercury xenon lamp was used as anirradiation light source. An interference filter VPF-50C-10-25-36500(manufactured by Sigmakoki Co., Ltd.) was placed between the lightsource and the quartz mold. The illuminance directly under the quartzmold was 1 mW/cm² at a wavelength of 365 nm.

Under these conditions, the photoirradiation step was performed for 60seconds.

In the demolding step, the quart mold was raised at 0.5 mm/s.

The demolding force was measured with a compact tension/compression loadcell LUR-A-200NSA1 (manufactured by Kyowa Electronic Instruments Co.,Ltd.). The average demolding force of four measurements under the sameconditions was 149 N.

Example 2

A photo-curable composition (a-2) was prepared in the same manner as inExample 1 except that 0.5 parts by weight of the fluorine-containingsurfactant (C-1) was used as the (C) component.

The surface tension and the viscosity of the photo-curable composition(a-2) were 25.5 mN/m and 6.4 cP, respectively, as measured in the samemanner as in Example 1.

Measurement of Water Contact Angle

A photo-cured film of the photo-curable composition (a-2) prepared inthe same manner as in Example 1 had a water contact angle of 64 degrees.

Measurement of Demolding Force

The average demolding force of the photo-curable composition (a-2) was128 N as measured in the same manner as in Example 1.

Example 3

A photo-curable composition (a-3) was prepared in the same manner as inExample 1 except that 2.0 parts by weight of the fluorine-containingsurfactant (C-1) was used as the (C) component.

The surface tension and the viscosity of the photo-curable composition(a-3) were 21.0 mN/m and 6.5 cP, respectively, as measured in the samemanner as in Example 1.

Measurement of Water Contact Angle

A photo-cured film of the photo-curable composition (a-3) prepared inthe same manner as in Example 1 had a water contact angle of 29 degrees.

Measurement of Demolding Force

The average demolding force of the photo-curable composition (a-3) was88 N as measured in the same manner as in Example 1.

Example 4

A mixed solution was prepared from the (A) component: 61.6 parts byweight of isobornyl acrylate (IB-XA manufactured by Kyoeisha ChemicalCo., Ltd.), 10 parts by weight of(2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate (MEDOL-10manufactured by Osaka Organic Chemical Industry Ltd.), and 22.4 parts byweight of hexanediol diacrylate (Viscoat #230 manufactured by OsakaOrganic Chemical Industry Ltd.), the (B) component: 3 parts by weight ofIrgacure 369 (manufactured by Ciba Japan K.K.), and the (C) component:2.2 parts by weight of pentadeca(ethylene glycol)mono-1H,1H,2H,2H-perfluorooctyl ether (F(CF₂)₆CH₂CH₂ (OCH₂CH₂)₁₅OH,manufactured by DIC). The mixed solution was passed through a 0.2 μmtetrafluoroethylene filter to yield a photo-curable composition (a-4)according to Example 4.

The surface tension and the viscosity of the photo-curable composition(a-4) were 24.9 mN/m and 7.1 cP, respectively, as measured in the samemanner as in Example 1.

Measurement of Water Contact Angle

A photo-cured film of the photo-curable composition (a-4) prepared inthe same manner as in Example 1 had a water contact angle of 64 degrees.

Measurement of Demolding Force

The average demolding force of the photo-curable composition (a-4) was99 N as measured in the same manner as in Example 1.

Example 5

A photo-curable composition (a-5) was prepared in the same manner as inExample 4 except that the (C) component was 1.3 parts by weight ofeicosa(ethylene glycol) mono-1H,1H,2H,2H-perfluorooctyl ether(F(CF₂)₆CH₂CH₂ (OCH₂CH₂)₂₀OH, manufactured by DIC).

The surface tension and the viscosity of the photo-curable composition(a-5) were 27.2 mN/m and 7.0 cP, respectively, as measured in the samemanner as in Example 1.

Measurement of Water Contact Angle

A photo-cured film of the photo-curable composition (a-5) prepared inthe same manner as in Example 1 had a water contact angle of 72 degrees.

Measurement of Demolding Force

The average demolding force of the photo-curable composition (a-5) was118 N as measured in the same manner as in Example 1.

Example 6

A mixed solution was prepared from the (A) component: 61.6 parts byweight of isobornyl acrylate (IB-XA manufactured by Kyoeisha ChemicalCo., Ltd.), 10 parts by weight of(2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate (MEDOL-10manufactured by Osaka Organic Chemical Industry Ltd.), and 22.4 parts byweight of hexanediol diacrylate (Viscoat #230 manufactured by OsakaOrganic Chemical Industry Ltd.), the (B) component: 3 parts by weight of2,2-dimethoxy-2-phenylacetophenone (Irgacure 651 manufactured by BASF),and the (C) component: 1.1 parts by weight of pentadeca(ethylene glycol)mono-1H,1H,2H,2H-perfluorooctyl ether (F(CF₂)₆CH₂CH₂ (OCH₂CH₂)₁₅OH,manufactured by DIC).

The mixed solution was passed through a 0.2 μm tetrafluoroethylenefilter to yield a photo-curable composition (a-6) according to Example6.

The surface tension and the viscosity of the photo-curable composition(a-6) were 26.1 mN/m and 6.6 cP, respectively, as measured in the samemanner as in Example 1.

Measurement of Water Contact Angle

A photo-cured film of the photo-curable composition (a-6) prepared inthe same manner as in Example 1 had a water contact angle of 58 degrees.

Measurement of Demolding Force

The light source was an ultrahigh-pressure mercury lamp. An interferencefilter was placed between the light source and a quartz mold. Lighthaving a wavelength of 313±5 nm can selectively pass through theinterference filter. The illuminance directly under the quartz mold was38.5 mW/cm² at a wavelength of 313 nm.

1440 droplets of 11 pL of the photo-curable composition (a-6) weresubstantially uniformly dropped by an ink jet method on a 26×33 mmregion of a 300-mm silicon wafer including an adhesion-promoting layerhaving a thickness of 3 nm as an adhesion layer.

A 26×33 mm quartz mold having no surface treatment and no pattern wasbrought into contact with the silicon wafer.

30 seconds after that, photoirradiation was performed for 5 seconds.

After the photoirradiation, the quartz mold was removed. The demoldingforce was measured with a load cell. The average demolding force ofthree measurements under the same conditions was 48.7 N. This demoldingforce was lower than that in Comparative Example 3 described below.

Example 7

A photo-curable composition (a-7) was prepared in the same manner as inExample 6 except that the (C) component was 2.2 parts by weight ofpentadeca(ethylene glycol) mono-1H,1H,2H,2H-perfluorooctyl ether(F(CF₂)₆CH₂CH₂ (OCH₂CH₂)₁₅OH, manufactured by DIC).

The surface tension and the viscosity of the photo-curable composition(a-7) were 23.9 mN/m and 6.7 cP, respectively, as measured in the samemanner as in Example 1.

Measurement of Water Contact Angle

A photo-cured film of the photo-curable composition (a-7) prepared inthe same manner as in Example 1 had a water contact angle of 9 degrees.

Measurement of Demolding Force

The average demolding force of the photo-curable composition (a-7) was49.1 N as measured in the same manner as in Example 6. This demoldingforce was lower than that in Comparative Example 3 described below.

Example 8

A photo-curable composition (a-8) was prepared in the same manner as inExample 6 except that the (B) component was 3 parts by weight of2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one (Irgacure 907manufactured by BASF).

The surface tension and the viscosity of the photo-curable composition(a-8) were 26.5 mN/m and 6.7 cP, respectively, as measured in the samemanner as in Example 1.

Measurement of Water Contact Angle

A photo-cured film of the photo-curable composition (a-8) prepared inthe same manner as in Example 1 had a water contact angle of 42 degrees.

Measurement of Demolding Force

The average demolding force of the photo-curable composition (a-8) was55.3 N as measured in the same manner as in Example 6. This demoldingforce was lower than that in Comparative Example 3 described below.

Comparative Example 1

A photo-curable composition (b-1) was prepared in the same manner as inExample 1 except that no (C) component was added.

The surface tension and the viscosity of the photo-curable composition(b-1) were 35.9 mN/m and 6.3 cP, respectively, as measured in the samemanner as in Example 1.

Measurement of Water Contact Angle

A photo-cured film of the photo-curable composition (b-1) prepared inthe same manner as in Example 1 had a water contact angle of 79 degrees.

Measurement of Demolding Force

The average demolding force of the photo-curable composition (b-1) was158 N as measured in the same manner as in Example 1, which was largerthan Examples 1 to 3.

Comparative Example 2

A photo-curable composition (b-2) was prepared in the same manner as inExample 4 except that no (C) component was added.

The surface tension and the viscosity of the photo-curable composition(b-2) were 31.5 mN/m and 6.8 cP, respectively, as measured in the samemanner as in Example 1.

Measurement of Water Contact Angle

A photo-cured film of the photo-curable composition (b-2) prepared inthe same manner as in Example 1 had a water contact angle of 81 degrees.

Measurement of Demolding Force

The average demolding force of the photo-curable composition (b-2) was143 N as measured in the same manner as in Example 1, which was largerthan Examples 4 and 5.

Comparative Example 3

A photo-curable composition (b-3) was prepared in the same manner as inExample 6 except that no (C) component was added.

The surface tension and the viscosity of the photo-curable composition(b-3) were 28.1 mN/m and 6.4 cP, respectively, as measured in the samemanner as in Example 1.

Measurement of Water Contact Angle

A photo-cured film of the photo-curable composition (b-3) prepared inthe same manner as in Example 1 had a water contact angle of 94 degrees.

Measurement of Demolding Force

The average demolding force of the photo-curable composition (b-3) was56.5 N as measured in the same manner as in Example 6, which was largerthan Examples 6 to 8.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2011-246714, filed Nov. 10, 2011, which is hereby incorporated byreference herein in its entirety.

1. A photo-curable composition, comprising: a polymerizable monomer (A);a polymerization initiator (B); and a fluorine-containing surfactant(C), wherein a photo-cured product of the photo-curable composition hasa water contact angle of 74 degrees or less.
 2. The photo-curablecomposition according to claim 1, wherein the photo-cured product of thephoto-curable composition has a water contact angle of 70 degrees orless.
 3. The photo-curable composition according to claim 1, wherein thefluorine-containing surfactant (C) has a polar functional group at oneend.
 4. The photo-curable composition according to claim 3, wherein thefluorine-containing surfactant (C) has a perfluoroalkyl chain (C-a) atone end and a polar functional group (C-c) at the other end, and theperfluoroalkyl chain is linked to the polar functional group through apoly(alkylene oxide) chain (C-b1) or an alkyl chain (C-b2).
 5. Thephoto-curable composition according to claim 3, wherein thefluorine-containing surfactant (C) is at least one compound having thefollowing general formula (1):F(CF₂)₆(CH₂)_(m)(OCH₂CH₂)_(n)OH  (1) wherein m is an integer in therange of 1 to 3, and n is an integer in the range of 1 to
 100. 6. Thephoto-curable composition according to claim 1, wherein thepolymerization initiator (B) is 2,2-dimethoxy-2-phenylacetophenone. 7.The photo-curable composition according to claim 1, wherein thepolymerization initiator (B) is2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one.
 8. Apatterning method, comprising: placing the photo-curable compositionaccording to claim 1 on a substrate to be processed; bringing thephoto-curable composition into contact with a mold; irradiating thephoto-curable composition with light; and releasing the photo-curablecomposition from the mold after the irradiation to form a pattern out ofthe photo-curable composition on the substrate to be processed.
 9. Thepatterning method according to claim 8, wherein a surface of the mold incontact with the photo-curable composition is made of quartz.
 10. Thepatterning method according to claim 8, wherein the irradiation involvesirradiating the photo-curable composition with light through the moldhaving recessed and raised portions on its surface.
 11. A method formanufacturing a circuit board, comprising: etching or implanting ionsinto a substrate in accordance with a pattern formed by the patterningmethod according to claim 8, thereby forming a circuit structure.
 12. Anarticle, comprising: a substrate; and a cured product disposed on thesubstrate, the cured product having a pattern of the photo-curablecomposition according to claim
 1. 13. The photo-curable compositionaccording to claim 1, wherein the composition is used for nanoimpirnts.14. A photo-curable composition for nanoimpirnts, comprising: apolymerizable monomer (A); a polymerization initiator (B); and afluorine-containing surfactant (C), wherein a photo-cured product of thephoto-curable composition has a water contact angle of 70 degrees orless.